[TASK] Remove irc notification from travis.yml

irc is unused.

Resolves: #84347
Releases: master, 8.7
Change-Id: I6d52ca238d698d21a446da624438ac46d099b93b
Reviewed-on: https://review.typo3.org/56228


Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Tested-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Reviewed-by: Mathias Brodala <mbrodala@pagemachine.de>
Tested-by: Mathias Brodala <mbrodala@pagemachine.de>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>